Zapco Z100C2-SL

First off, thanks to my friend on the PG forum, Sactownstang for hooking me up with his amp to test.

This review will be broken up into three sections, design/construction, test measurements, and finally subjective opinions.

Design/Construction:

Zapco is a very old player in the car audio world.  They have been known for competition quality products with underrated output specs since their beginning.  The Z100C2-SL is by no means a modern amplifier, but it was originally offered at a point in Zapco's history were they had significant experience.

Nearly every aspect of the amp has been carefully thought out.  The amp is plain, but oozes quality.

Zapco uses a form of balanced interconnect technology, which they refer to as Symbilink.  Symbilink is identical to a common balanced line, except for the addition of a positive and a negative voltage rail to the connector.  This allows the Symbilink capable amplifier to power an upstream processor, and thereby simplify the installation.  I had to make an adapter to use the amplifier.

Zapco used cheap gain control pots, but at least they did included a stereo set so that last little bit of matching can be performed.  There is a switch for balanced/unbalanced input, and mono (left only input needed) opperation.

One complaint I have had with Zapco is their connections for power, ground, and the rest.  They use a simple and common barrier strip.  Although this works just fine, I feel it is too cheap for an amp of this caliber, and should have been replaced with some type of custom interface.

Zapco has an onboard 30A fuse mounted in the side of the amp.  This is a nice addition, and was cleanly implemented.

Zapco went to great lengths to make sure the amp was clean, simple, and long lasting.  Every panel on the amplifier is made of aluminum.  Most manufactures use an aluminum extrusion for the heatsink, and then stick painted steel endplates on this extrusion.  In several years, these endplates will have rusted, and caused the amplifier to look awful.  Precision Power is another manufacturer who has historically used aluminum endplates.  PPI however uses a steel bottom, as it is needed for their "finger clamp" device mounting system.  The serial number is printed on the bottom of the amp, and also internally.

Another area I am somewhat disappointed with is the addition of the amplifiers power spec to the top of the heatsink.  Not only does this align the amp with flea market products, it also is pointless, as these amps are so underrated the numbers are useless.

The board used in the amplifier is high quality.  It is fully coated, and should there for be resilient to any loose strands of wire making their way into the amp.  I have no clue how they would get there though, as there are no holes in the amp anywhere.

The amplifier uses very common parts for amplification.  The outputs are TIP36C, and TIP35C bipolar devices.  Each is rated for 25A capability, which rivals many MOSFETs, yet is far more linear.

The preamp/voltage gain, and output pre driving is all done with TIP31C, and TIP32C devices.  These are some of the most common devices in existence. 

For power supply switching, 4 very common IRFZ46E are used.

Power supply rectification is done in a very nice way.  Instead of using the integrated dual diodes (common anode one side, and common cathode the other) like I am used to in PG amps, Zapco chose to use 4 single diodes.  This has many advantages.  First off, all the diodes are the same, and easy to acquire.  Second, they are individually much higher current capable.  With 4 of them his amp should be able to handle impressive amounts of current draw.

The two input supply capacitors are 3,300uF, which is plenty large enough for an amp this size.

For rail capacitance, the amp uses 4 1,000uF 50V caps.

The transformer is not the cleanest I have seen by any means, but is well wound, and solid.

The power supply PWM controller is a very common one,  The exact same is used in most PG amps, the SG3525.

Like PG amps, output inductors are used to eliminate high frequency switching noise, and optimize the loading on the output devices.

I can't really complain about any of the parts used in the Z100C2-SL.  They are all more than enough for the amp, and I don't see any area where it is lacking.

I am not 100% sure how the gain stage of the amp works, but based on the TIP31C mounted next to each of the output pairs on the heatsink, it is very possible this amp uses a Class A voltage gain stage.  This device may however just be the bias control transistor, but I can't be certain of that unless I pulled the board and studied the layout (something I don't want to do).

Test Measurements:

Testing on this amp went very simply.  There is no on board crossover, so all I could measure for frequency response was the overall amp frequency response.

Output voltage was 14V AC unclipped with a sine wave, and 14V DC source input.  This should allow for about 50W output per channel into 4 ohms, which is twice what it is rated at.

Subjective Measurements:

I first listened to the amp for several hours to see what I thought of it. 

It is very clean, and forceful.  I was using 8ohm home speakers so they should only be getting about 25W tops, and the amp performed like a significantly larger amplifier.  Bass response was great (for my home speakers), and had more detail to it than most other amps.

I finally decided to pull out the reference M25 and do an A/B comparison.

After many hours, I could not tell the difference.  No matter how hard I tried, they sounded the same.

The next day I thought I would give the test another try, this time with a much better source.  Assuming both these amps are excellent, my guess was a better source would bring out any difference in them.

Well, after several hours of A/B testing with a Sony ES CA80ES CD player (the best source I had available, I still could not tell the amplifiers apart.

In the comparison, I did notice one nice difference in the Zapco.  It ran far cooler.  It does have less output voltage, but both were set the same, so this would not be an issue.  The whole chassis of the Zapco is aluminum, whereas the M25 is part aluminum and part steel.  I feel the additional aluminum in the Zapco, and its very thin fins allowed it to remain far cooler.

Final Thoughts:

This Z100CS-SL is a great amp.  It is well designed, and very well built.  I don't see any major areas where anyone can complain about any part of it.  I don't know if it beats out my M25, largely due to the price difference (don't know what that is exactly, but I am sure the Zapco is far more expensive), but it is an amplifier I would strongly consider installing in my vehicle.